An update to the #2639 fix
diff --git a/system/helpers/form_helper.php b/system/helpers/form_helper.php
index 20379ef..7112a99 100644
--- a/system/helpers/form_helper.php
+++ b/system/helpers/form_helper.php
@@ -717,6 +717,10 @@
 		{
 			return ($default === TRUE) ? ' checked="checked"' : '';
 		}
+		elseif (is_array($input) && in_array($value, $input, TRUE))
+		{
+			return ' checked="checked"';
+		}
 
 		return ($input === $value) ? ' checked="checked"' : '';
 	}